The objectives of this research project are to define, with respect to age, the chemical, biochemical, and immunologic properties of proteoglycans isolated from normal lung parenchyma and the tracheobronchial tree in humans and a rabbit model system. A secondary objective will be to compare the properties of these proteoglycans with those produced by lung cells grown in culture. Proteoglycans will be extracted from the tissue under dissociative conditions with guanidinium hydrochloride in the presence of protease inhibitors and purified under dissociative or associative conditions in cesium chloride density gradients or by ion exchange or selective precipitation procedures. A direct structural comparison will be made between fractions isolated from the hyaline cartilage of the tracheobronchial tree and lung. Proteoglycan fractions obtained will be characterized, with respect to size and heterogeneity, by a variety of physical and chemical techniques, including analytical ultracentrifugation, gel filtration, column chromatography, and electrophoresis before and after treatment with enzymes. The amino acid, sugar, and glycosaminoglycan content will also be determined by chemical and enzymatic procedures. Special emphasis will be given to determining the nature of the heterogeneity, hybrid structure of glycosaminoglycan chains, and the nature of glycopeptide materials that may be present. Immunochemical procedures, both direct and of the radioimmunoassay type, will be used to compare proteoglycan protein core(s). Attempts will be made to compare these results with proteoglycans produced by lung cell preparations obtained by standard procedures in primary culture or after growth in the presence of connective tissue components.